This invention relates to an ignition timing controller for an internal combustion engine.
The setting of an ignition timing of an internal combustion engine is performed so that the engine can be operated most efficiently. It is generally preferred to set the igniting timing of the engine so as to approach to a MBT (Minimum advance for best torque) as near as possible in a range that the engine does not knock.
However, a prior-art ignition timing controller which is heretofore used mostly employs a mechanical structure, is not accordingly stabilized for the ignition angle leading characteristic in the irregularity of the products and in the ageing change. The actual ignition timing of the engine is set at the side considerably delayed from the above-described desired ignition timing so as to prevent the knocking of the engine, causing a deterioration in the efficiency of the engine. Even if the ignition timing controller which has less irregularity and ageing change is employed, knocking phenomenon of the engine depends upon the suction air temperature, humidity and further air-fuel ratio of the engine. Accordingly, even if the ignition timing is set so as not to cause a knocking under a certain operating conditions of the engine, the knocking might occur under different conditions of the engine.
The ignition timing can be matched to a value which does not cause a knocking by detecting the occurrence of the knocking and controlling the ignition timing delay even if an error occurs in the ignition leading angle due to irregularity in the product and the difference of the operating conditions of the engine. Under such conditions, the knocking frequently occurs at the accelerating time rather than the normally operating time of the engine, and the level of the knocking becomes large. It is necessary to provide a larger controlling angle than the normal time so as to sufficiently suppress the knocking at the transient time.